If [the late Mexican blogger Castro] was being tracked electronically, what could Castro have done to reduce the danger? "She could have used Tor," says Smyth, main author of the CPJ guide. Tor is described on its Web site as free software that "prevents anyone from learning your location or browsing habits." It also is known as a censorship circumvention tool.

After the attack, the Telegraph in London reported that journalists in Homs had worried "that Syrian forces had 'locked on' to their satellite phone signals and attacked the buildings from which they were coming."

Colvin filed stories via a satellite uplink and had been vocal about the Syrian government's human rights violations during interviews on CNN and other news outlets just before the attack. Without precautions, the journalists could have been easy targets, Smyth says. CPJ advises against multiple parties transmitting from the same location in a hot zone like Homs.

For the full American Journalism Review article by Sherry Ricchiardi, please click here.